Dessication of conducting tissue by glycerine enhances the conducting power. Local application of cold depresses or arrests the conduction. Application of poison permanently abolishes the power of conduction. Conductivity is modified by the effect of season, being higher in summer than in winter. The power of conduction is also modified by age. In young specimens the conducting power is low, the conductivity is at its maximum in fully grown organs; but a decline of conductivity sets in with age. The tonic condition of a tissue has an influence on conductivity. In an optimum condition, the velocity is the same for feeble or strong stimulus. Excessive stimulation induces a temporary depression of the conducting power. The effects are different in a sub-tonic tissue: velocity of transmission increases with intensity of stimulus; after-effect of stimulus is to initiate or enhance the conducting power. The conducting path is canalised by stimulus. VII.--ON ELECTRIC CONTROL OF EXCITATORY IMPULSE _By_ SIR J. C. BOSE. I have in my previous works[L] described investigations on the conduction of excitation in _Mimosa pudica_. It was there shown that the various characteristics of the propagation of excitation in the conducting tissue of the plant are in every way similar to those in the animal nerve. Hence it appeared probable that any newly found phenomenon in the one case was likely to lead to discovery of a similar phenomenon in the other. [L] BOSE--“Comparative Electro-Physiology” (1907). Longmans, Green and Co. As the transmission of excitation is a phenomenon of propagation of molecular disturbance in the conducting vehicle, it appeared that the excitatory impulse could be controlled by inducing in the conducting tissue two opposite ‘molecular dispositions’, using that term in the widest sense. The possibility of accomplishing this by the directive action of an electric current had attracted my attention for many years. METHOD OF CONDUCTIVITY BALANCE.